I have a small Node.js / Express app deployed to Heroku.
I'd like to use a lightweight database like NeDB to persist some data. Is it possible to periodically backup / copy a file from Heroku if I used this approach?
File-based databases aren't a good fit for Heroku due to its ephemeral filesystem (bold added):
Each dyno gets its own ephemeral filesystem, with a fresh copy of the most recently deployed code. During the dyno’s lifetime its running processes can use the filesystem as a temporary scratchpad, but no files that are written are visible to processes in any other dyno and any files written will be discarded the moment the dyno is stopped or restarted. For example, this occurs any time a dyno is replaced due to application deployment and approximately once a day as part of normal dyno management.
Depending on your use case I recommend using a client-server database (this looks like a good fit here) or something like Amazon S3 for file storage.
I'm going to move .NET project into containers and want to do this in a correct way.
At the moment development environment is a simple:
Each developer has his-own SQL Server deployed on his PC and all DB lives there
During development ASP.NET project runs in IIS Express
Connection string to connect to DB looks like this "Data Source=.;Initial Catalog=DB;Trusted_Connection=True". Using "." as data source helps unify web.config and have it working on each developer's PC
Everything is simple.
Right now because of many reasons I would like to move into containers and faced with few issues. All of them I think because of my misunderstanding of some principle of the containers and that is why I need somebody small help to avoid waste of time doing wrong things.
The main issues linked with working with DB
How to create a container with SQL Server and list of DB to be able
to work with it on the same way how we work with it right now. I
mean - OS is started, SQL server service is started and I can
connect to DB via MS Management Studio. The main concern is a having
all DB in safe. I've understood how to mount volume with persistence
storage to have Backup creation on it. But can I work on the same way with DB to be sure that each time when container starts I have all DB working?
How I can then configure docker-compose file in project's solution
to connect to that container with working DB and don't start new
one?
And how to do this on the way to have connection string the same on each developer's PC? I mean - avoid having IP address as data source and still works with "." or "localhost" or something which could be the same for everyone?
If my understand of containers is incorrect and I should use
deployed in my PC SQL server - how to configure docker-compose file
to connect to SQL server in the host via "localhost" avoiding
defining IP address or make it works the same on each PC?
How to make it works then on production I know because we have there one SQL Server with the only one connection string and it's not an issue. But how to configure dev. environment - it's a question for me. And 1 week guides reading really didn't help. Maybe I missed something and somebody could just point to correct article which could give me some answers.
Thank you for your help.
Docker Compose for Sql Server
docker-compose.yml
version: '2'
services:
app-mssql:
image: microsoft/mssql-server-linux:latest
# volumes are not supported on macOS
# uncomment bellow volume and replace volume with relative or absolute path of the host
# volumes:
# - ~/volumes/jhipster/tempdb/mssql/:/var/opt/mssql/data/
environment:
- ACCEPT_EULA=Y
- SA_PASSWORD=yourStrong(!)Password
ports:
- 1433:1433
Requirements:
RAM : 2GB
Environment Variables
ACCEPT_EULA=Y
SA_PASSWORD=<your_strong_password>
MSSQL_PID=<your_product_id | edition_name> (default: Developer)
ACCEPT_EULA confirms your acceptance of the End-User Licensing Agreement.
SA_PASSWORD is the database system administrator (userid = 'sa') password used to connect to SQL Server once the container is running. Important note: This password needs to include at least 8 characters of at least three of these four categories: uppercase letters, lowercase letters, numbers and non-alphanumeric symbols.
MSSQL_PID is the Product ID (PID) or Edition that the container will run with.
Acceptable values:
Developer : This will run the container using the Developer Edition (this is the default if no MSSQL_PID environment variable is supplied)
Express : This will run the container using the Express Edition
Standard : This will run the container using the Standard Edition
Enterprise : This will run the container using the Enterprise Edition
EnterpriseCore : This will run the container using the Enterprise Edition Core
valid product id : This will run the container with the edition that is associated with the PID
NOTE : Here you can find the detiled documentation on docker hub microsoft/mssql-server-linux
I am just starting to get my head wrapped around continuous deployment with Jenkins, but I am running into some roadblocks and I haven't really found very many good, definitive resources on the topic in regards to ASP.NET applications.
I have set up a local build server than successfully pulls down code from a SVN repo, and builds it OK with MSBuild. This works well so far, but now I'd like to automate pushing this compiled code to a development server.
My problem is this - from what I gather based on what I read (which may be an incorrect assumption...) is that the staging server is typically within the same network as the build server, meaning you can share network resources, servers, etc.
In my case, I want to run the Jenkins server on a remote VPS, then deploy to other remote VPSes (so, essentially individual isolated machines communicating with each other).
I have seen alot of terms, but I am very new in my Sys Admin / DevOps type skills.
So, my question is this:
Is it even possible to, using Jenkins on a VPS, to then deploy to any particular server I choose? (I have full access to all of them, so if its a security thing, I can fix that... but they are not within the same network/domain)
What is the method to achieve this? I've seen xcopy, Web Deployment Packages (msdeploy), batch scripts, etc. mentioned, but not really a guidance behind what to use in what situations. Are any of these methods useful to achieve my goal?
Thanks for any help or guidance!
How is your Powershell? ;) You should check out psake.
psake is a build automation tool written in PowerShell. It avoids the
angle-bracket tax associated with executable XML by leveraging the
PowerShell syntax in your build scripts. psake has a syntax inspired
by rake (aka make in Ruby) and bake (aka make in Boo), but is easier
to script because it leverages your existent command-line knowledge.
psake is pronounced sake – as in Japanese rice wine. It does NOT rhyme
with make, bake, or rake.
You can deploy your files to the target server through SSH. Jenkins do support transfers through SSH. All you need to do is setting up a SSH server ex : CopSSH and a user account with admin permissions. and configuring the Jenkins to transfer through SSH.
Create host configurations in the main Jenkins configuration
Add an SSH Server
Add the public key to the remote server (the build server)
Click "Test Configuration"
Save
Configure a job to Publish Over SSH (Post Build Action)
Add Transfer Set.
Refer Publish Over SSH For More details
i have 3 servers and install centos 5.5 ,drupal
now i want all server sync file and database
thank you
If you want to have this fully automatic:
Declare on server as master/source server. Any changes on the client machines are overwritten.
Use crontab to start the synchronization repeatedly on the client machines and to start drupal cron on the master machine.
Install ssh and install key files without pass phrase to get secure, reliable and unatended communication between the servers.
Use the backup and migrate module to get a MySql backup triggered by cron.
Do the file synchronization with rsync and keep an eye on file permissions to make sure files are accessible by the apache user on the destination servers.
Import the result of the backup and migrate backup into the client servers db.
A completely different approach would be to use the views module and create RSS Feeds of your nodes. The other servers could read and view them or update their data.
Again a different case: If you want to setup your 3 servers for load balancing / fail over purposes choose a distributed file system and a mirror setup for your db. This way the systems look like one big logical machine with the advantage that single physical machines can crash without crashing the whole system.
To deploy a new version of our website we do the following:
Zip up the new code, and upload it to the server.
On the live server, delete all the live code from the IIS website directory.
Extract the new code zipfile into the now empty IIS directory
This process is all scripted, and happens quite quickly, but there can still be a 10-20 second downtime when the old files are being deleted, and the new files being deployed.
Any suggestions on a 0 second downtime method?
You need 2 servers and a load balancer. Here's in steps:
Turn all traffic on Server 2
Deploy on Server 1
Test Server 1
Turn all traffic on Server 1
Deploy on Server 2
Test Server 2
Turn traffic on both servers
Thing is, even in this case you will still have application restarts and loss of sessions if you are using "sticky sessions". If you have database sessions or a state server, then everything should be fine.
The Microsoft Web Deployment Tool supports this to some degree:
Enables Windows Transactional File
System (TxF) support. When TxF support
is enabled, file operations are
atomic; that is, they either succeed
or fail completely. This ensures data
integrity and prevents data or files
from existing in a "half-way" or
corrupted state. In MS Deploy, TxF is
disabled by default.
It seems the transaction is for the entire sync. Also, TxF is a feature of Windows Server 2008, so this transaction feature will not work with earlier versions.
I believe it's possible to modify your script for 0-downtime using folders as versions and the IIS metabase:
for an existing path/url:
path: \web\app\v2.0\
url: http://app
Copy new (or modified) website to server under
\web\app\v2.1\
Modify IIS metabase to change the website path
from \web\app\2.0\
to \web\app\v2.1\
This method offers the following benefits:
In the event new version has a problem, you can easily rollback to v2.0
To deploy to multiple physical or virtual servers, you could use your script for file deployment. Once all servers have the new version, you can simultaneously change all servers' metabases using the Microsoft Web Deployment Tool.
You can achieve zero downtime deployment on a single server by utilizing Application Request Routing in IIS as a software load balancer between two local IIS sites on different ports. This is known as a blue green deployment strategy where only one of the two sites is available in the load balancer at any given time. Deploy to the site that is "down", warm it up, and bring it into the load balancer (usually by passing a Application Request Routing health check), then take the original site that was up, out of the "pool" (again by making its health check fail).
A full tutorial can be found here.
I went through this recently and the solution I came up with was to have two sites set up in IIS and to switch between them.
For my configuration, I had a web directory for each A and B site like this:
c:\Intranet\Live A\Interface
c:\Intranet\Live B\Interface
In IIS, I have two identical sites (same ports, authentication etc) each with their own application pool. One of the sites is running (A) and the other is stopped (B). the live one also has the live host header.
When it comes to deploy to live, I simply publish to the STOPPED site's location. Because I can access the B site using its port, I can pre-warm the site so the first user doesn't cause an application start. Then using a batch file I copy the live host header to B, stop A and start B.
OK so since everyone is downvoting the answer I wrote way back in 2008*...
I will tell you how we do it now in 2014. We no longer use Web Sites because we are using ASP.NET MVC now.
We certainly do not need a load balancer and two servers to do it, that's fine if you have 3 servers for every website you maintain but it's total overkill for most websites.
Also, we don't rely on the latest wizard from Microsoft - too slow, and too much hidden magic, and too prone to changing its name.
Here's how we do it:
We have a post build step that copies generated DLLs into a 'bin-pub' folder.
We use Beyond Compare (which is excellent**) to verify and sync changed files (over FTP because that is widely supported) up to the production server
We have a secure URL on the website containing a button which copies everything in 'bin-pub' to 'bin' (taking a backup first to enable quick rollback). At this point the app restarts itself. Then our ORM checks if there are any tables or columns that need to be added and creates them.
That is only milliseconds downtime. The app restart can take a second or two but during the restart requests are buffered so there is effectively zero downtime.
The whole deployment process takes anywhere from 5 seconds to 30 minutes, depending how many files are changed and how many changes to review.
This way you do not have to copy an entire website to a different directory but just the bin folder. You also have complete control over the process and know exactly what is changing.
**We always do a quick eyeball of the changes we are deploying - as a last minute double check, so we know what to test and if anything breaks we ready. We use Beyond Compare because it lets you easily diff files over FTP. I would never do this without BC, you have no idea what you are overwriting.
*Scroll to the bottom to see it :( BTW I would no longer recommend Web Sites because they are slower to build and can crash badly with half compiled temp files. We used them in the past because they allowed more agile file-by-file deployment. Very quick to fix a minor issue and you can see exactly what you are deploying (if using Beyond Compare of course - otherwise forget it).
Using Microsoft.Web.Administration's ServerManager class you can develop your own deployment agent.
The trick is to change the PhysicalPath of the VirtualDirectory, which results in an online atomic switch between old and new web apps.
Be aware that this can result in old and new AppDomains executing in parallel!
The problem is how to synchronize changes to databases etc.
By polling for the existence of AppDomains with old or new PhysicalPaths it is possible to detect when the old AppDomain(s) have terminated, and if the new AppDomain(s) have started up.
To force an AppDomain to start you must make an HTTP request (IIS 7.5 supports Autostart feature)
Now you need a way to block requests for the new AppDomain.
I use a named mutex - which is created and owned by the deployment agent, waited on by the Application_Start of the new web app, and then released by the deployment agent once the database updates have been made.
(I use a marker file in the web app to enable the mutex wait behaviour)
Once the new web app is running I delete the marker file.
The only zero downtime methods I can think of involve hosting on at least 2 servers.
I would refine George's answer a bit, as follows, for a single server:
Use a Web Deployment Project to pre-compile the site into a single DLL
Zip up the new site, and upload it to the server
Unzip it to a new folder located in a folder with the right permissions for the site, so the unzipped files inherit the permissions correctly (perhaps e:\web, with subfolders v20090901, v20090916, etc)
Use IIS Manager to change the name of folder containing the site
Keep the old folder around for a while, so you can fallback to it in the event of problems
Step 4 will cause the IIS worker process to recycle.
This is only zero downtime if you're not using InProc sessions; use SQL mode instead if you can (even better, avoid session state entirely).
Of course, it's a little more involved when there are multiple servers and/or database changes....
To expand on sklivvz's answer, which relied on having some kind of load balancer (or just a standby copy on the same server)
Direct all traffic to Site/Server 2
Optionally wait a bit, to ensure that as few users as possible have pending workflows on the deployed version
Deploy to Site/Server 1 and warm it up as much as possible
Execute database migrations transactionally (strive to make this possible)
Immediately direct all traffic to Site/Server 1
Deploy to Site/Server 2
Direct traffic to both sites/servers
It is possible to introduce a bit of smoke testing, by creating a database snapshot/copy, but that's not always feasible.
If possible and needed use "routing differences", such as different tenant URL:s (customerX.myapp.net) or different users, to deploy to an unknowing group of guinea pigs first. If nothing fails, release to everyone.
Since database migrations are involved, rolling back to a previous version is often impossible.
There are ways to make applications play nicer in these scenarios, such as using event queues and playback mechanisms, but since we're talking about deploying changes to something that is in use, there's really no fool proof way.
This is how I do it:
Absolute minimum system requirements:
1 server with
1 load balancer/reverse proxy (e.g. nginx) running on port 80
2 ASP.NET-Core/mono reverse-proxy/fastcgi chroot-jails or docker-containers listening on 2 different TCP ports
(or even just two reverse-proxy applications on 2 different TCP ports without any sandbox)
Workflow:
start transaction myupdate
try
Web-Service: Tell all applications on all web-servers to go into primary read-only mode
Application switch to primary read-only mode, and responds
Web sockets begin notifying all clients
Wait for all applications to respond
wait (custom short interval)
Web-Service: Tell all applications on all web-servers to go into secondary read-only mode
Application switch to secondary read-only mode (data-entry fuse)
Updatedb - secondary read-only mode (switches database to read-only)
Web-Service: Create backup of database
Web-Service: Restore backup to new database
Web-Service: Update new database with new schema
Deploy new application to apt-repository
(for windows, you will have to write your own custom deployment web-service)
ssh into every machine in array_of_new_webapps
run apt-get update
then either
apt-get dist-upgrade
OR
apt-get install <packagename>
OR
apt-get install --only-upgrade <packagename>
depending on what you need
-- This deploys the new application to all new chroots (or servers/VMs)
Test: Test new application under test.domain.xxx
-- everything that fails should throw an exception here
commit myupdate;
Web-Service: Tell all applications to send web-socket request to reload the pages to all clients at time x (+/- random number)
#client: notify of reload and that this causes loss of unsafed data, with option to abort
# time x: Switch load balancer from array_of_old_webapps to array_of_new_webapps
Decomission/Recycle array_of_old_webapps, etc.
catch
rollback myupdate
switch to read-write mode
Web-Service: Tell all applications to send web-socket request to unblock read-only mode
end try
A workaround with no down time and I am regularly using is:
Rename running .NET core application dll to filename.dll.backup
Upload the new .dll (web application is available and serving the requests while file is being uploaded)
Once upload is complete recycle the Application Pool. Either Requires RDP Access to server or function to recycle application pool in your hosting control panel.
IIS overlaps the app pool when recycling so there usually isn’t any downtime during a recycle. So requests still come in without every knowing the app pool has been recycled and the requests are served seamlessly with no downtime.
I am still searching for more better method than this..!! :)
IIS/Windows
After trying every possible solution we use this very simple technique:
IIS application points to a folder /app that is a symlink (!) to /app_green
We deploy the app to /app_blue
We change the symlink to point to /app_blue (the app keeps working)
We recycle the application pool
Zero downtime, but the app does choke for 3-5 seconds (JIT compilation and other initialization tasks)
Someone called it a "poor man's blue-green deployment" without a load balancer.
Nginx/linux
On nginx/linux we use "proper" blue-green deployment:
nginx reverse proxy points to localhost:3000
we deploy to localhost:3001
warmup the localhost:3001
switch the reverse proxy
shot down localhost:3000
(or use docker)
Both windows and linux solutions can be easily automated with powershell/bash scripts and invoked via Github Actions or a similar CD/CI engine.
I would suggest keeping the old files there and simply overwriting them. That way the downtime is limited to single-file overwrite times and there is only ever one file missing at a time.
Not sure this helps in a "web application" though (i think you are saying that's what you're using), which is why we always use "web sites". Also with "web sites" deploying doesn't restart your site and drop all the user sessions.