Background:
We are have noticed that in production and in some staging environments, that the onClick handlers on a SSR page are failing to be called. By comparing working and non-working (npm run start) deployments we've determined that the non-working deployments are not calling the render() methods of the components on the page immediately after page reload, whereas the working deployments do. We are assuming that means that hydration is not occurring.
Development deployments (npm run dev) work flawlessly
We are seeing no browser-side console messages.
We are seeing no server side warnings
The npm build --debug suggests only to upgrade to the new ChunkGraph API. Otherwise no warnings.
We are now wondering...
QQ:
Short of starting with a fresh create-next-app again and gradually evolving the app towards our current implementation until it breaks, what are the suggested ways of determining the root cause(s) of a problem like this?
For some reason, my hydration issues only showed up in production, and only on the server. Running next build and next start didn't show any errors. Since user3624334's answer didn't really help me, I figured I'd reply with how I ended up finding the culprit.
Since I deploy to Vercel, and use Vercel's review apps, I ended up creating a Pull Request where I remove half of the page that was having the hydration issues, and continued bisecting until I found out which component was causing the issues. It took me three tries to find the component.
Once I had the component it was quite easy to figure out what was causing the issues (for me the hydration issue was caused by a timestamp being rendered in different ways).
This also explains why user3624334's answer didn't work for me, since I opened the page straight after building, at which point the time was still the same as during next build!
One challenge here is that it appears that when SSR page hydration fails in next.js, a warning message will not necessarily be generated.
I hope someone has a better suggestion than the following, but I will offer this human script that worked several times for me:
git checkout -b "hydration-problem-02" to create a branch for this effort
add a console.log('render called') to the top of the render() method of pages/_app.js. This should produce a message on each hydrate, making it easy to notice when the page does/does-not hydrate.
Then repeatedly:
simplify a significant portion of the app.
npm run dev to run in dev mode
confirm that your change did not break the app in unexpected ways
rm .next/ node_modules/ package-lock.json
npm install && npm run build && npm run start
confirm that the above command completed successfully
refresh the page in the browser
check for the message in the browser console.
git commit -am "msg that indicates what you changed and if it helped"
if the problem remains, repeat these steps
Doing the commits above should help make the process more fool-proof. Ex. If you think you might have forgotten to test in production mode, you can go back to that commit and retest to confirm you did not mis-test.
Once you have a working and non-working commit of the app, you can do a binary search for the error, either adding or removing smaller and smaller pieces of function.
The root causes of quiet hydration failures I've seen include:
two modules that mutually import each other
an import '..../bootstrap.js' in a component rather than _app.js
I have a strange issue. I build my Meteor app and run it on android device using -
meteor run android-device --mobile-server=<my_aws_ip>:3000
When the app deploys immediately it connects to the server (and my javascripts etc works). After a few seconds, the page refreshs and none of the javascript callbacks work. Please help me debug this issue.
More information: If I change the client (and not the server), and deploy it, for the first few seconds, the changed client gets shown on the phone. After the first few seconds, the version which is present on the server is shown. So I think Cordova or Meteor is trying to fetch the client code from the server, which is breaking the app. Is there a way to prevent this behavior?
Even more data points -
My aws code does NOT have android and ios platforms installed. Because of this, I think the cordova plugins are not installed, causing a JS break somewhere.
Easiest fix I can think of is remove cordova autoupdate. This is being added by meteor-platform package. If I clone meteor-platform and comment out the cordova autoupdate, the app doesn't load.
Is there another way of removing autoupdate?
This sounds like you have a different version of your app deployed at the mobile-server address.
The local code is run in development mode. Your AWS one is likely in production mode (and may contain a syntax error).
When you run your app it sees the code is different and fetches the new/old (different) version with a hot code reload - hence the page refresh/flash.
To fix this, you need to find the syntax error in your code. It's best to view the ADB logger or run with meteor run --verbose android-device ....
This will provide a bit more information such as an Uncaught exception: cannot read .. of null error type error.
It's hard to say what the error is. The error prevents the rest of your code from executing. In production mode the entire project is one JS file. If there is an error of any kind half way along the file, the rest of the file will not execute.
Also, try loading <my_aws_ip>:3000 in your browser and watch for JS errors in the JS console.
You can also run it locally with --production to simulate a production build environment locally.
Enabling autoupdate but without a page refresh:
Reload._reload = function (options) {
console.log("Next load will load new version");
};
I have deployed an angular-fullstack (Yeoman generator) app to Openshift successfully, however, when I make changes and try to push the changes to Openshift via the command "grunt buildcontrol:openshift" I get the following error...
Unable to process task.
Warning: Required config property "buildcontrol.openshift" missing. Use --force to continue.
Has anyone come across this error and found a solution? If I try and force the task it does not do anything additional. I'm not quite sure what I need to be looking for, or adding.
I'm using
Meteor 1.0.2.1
sanjo:jasmine 0.9.1
velocity:html-reporter 0.3.2
https://doctorllama.wordpress.com/2014/09/22/bullet-proof-internationalised-meteor-applications-with-velocity-unit-testing-integration-testing-and-jasmine/ says I should be able to use console.log() to see output in the console.
But nothing happens for me.
If I move the call out of tests/jasmine into client/ or server/ then the output is on the terminal where meteor is run.
The html-reporter also has a section called Logs. Looking at the code it appears to have a reactive collection on VelocityLogs. My google-fu is failing me as I can find no information on how to get any output to display in this section.
What is the correct way of logging in jasmine tests?
In Chrome the client side logs are visible through the JavaScript Console.
But I still don't know where the server side logs might be.
I've run with DEBUG=1 JASMINE_DEBUG=1 VELOCITY_DEBUG=1 VELOCITY_DEBUG_MIRROR=1 and the console logs do not appear either.
Edit:
I've created a repo to provide an example of the problems at https://github.com/baerrach/meteor-velocity-issue-223.
If you are running server integration tests and they're not appearing, you may have found a bug!
Try running with:
VELOCITY_DEBUG=1 meteor
The logs should appear in the same place as the main meteor logs appear, prefixed with [velocity-mirror]
Does anyone know a good method to debug server side code?
I tried enable Node.js debug then use node-inspector but it does not show any of my code.
I end up using console.log but this is very inefficient.
Update: I found the following procedure works on my Linux machine:
When you run Meteor, it will spawn two processes
process1: /usr/lib/meteor/bin/node /usr/lib/meteor/app/meteor/meteor.js
process2: /usr/lib/meteor/bin/node /home/paul/codes/bbtest_code/bbtest02/.meteor/local/build/main.js --keepalive
You need to send kill -s USR1 on process2
Run node-inspector and you can see your server code
On my first try, I modify the last line on meteor startup script in /usr/lib/meteor/bin/meteor to
exec "$DEV_BUNDLE/bin/node" $NODE_DEBUG "$METEOR" "$#"
and run NODE_DEBUG=--debug meteor on command prompt. This only put --debug flag on process1 so I only see meteor files on node-inspector and could not find my code.
Can someone check this on Windows and Mac machine?
In Meteor 0.5.4 this has become a lot easier:
First run the following commands from the terminal:
npm install -g node-inspector
node-inspector &
export NODE_OPTIONS='--debug-brk'
meteor
And then open http://localhost:8080 in your browser to view the node-inspector console.
Update
Since Meteor 1.0 you can just type
meteor debug
which is essentially a shortcut for the above commands, and then launch node inspector in your browser as mentioned.
Update
In Meteor 1.0.2 a console or shell has been added. It may come in handy to output variables and run commands on the server:
meteor shell
Meteor apps are Node.js apps. When running a Meteor app with the meteor [run] command, you can configure the NODE_OPTIONS environment variable to start node in debug mode.
Examples of NODE_OPTIONS environment variable values:
--debug
--debug=47977 - specify a port
--debug-brk - break on the first statement
--debug-brk=5858 - specify a port and break on the first statement
If you export NODE_OPTIONS=--debug, all meteor command run from the same shell will inherit the environment variable. Alternatively, you can enable debugging just for one run, with NODE_OPTIONS="--debug=47977" meteor.
To debug, run node-inspector in a different shell, then go to http://localhost:8080/debug?port=<the port you specified in NODE_OPTIONS>, regardless of what node-inspector tells you to run.
To start node.js in debug mode, I did it this way:
open /usr/lib/meteor/app/meteor/run.js
before
nodeOptions.push(path.join(options.bundlePath, 'main.js'));
add
nodeOptions.push('--debug');
Here are additional practical steps for your to attach debugger eclipse:
use '--debug-brk' instead of '--debug' here, because it's easier for me to attach node.js using eclipse as debugger.
add 'debugger;' in the code where you want to debug.(I prefer this way personally)
run meteor in console
attach to node.js in eclipse(V8 tools, attach to localhost:5858)
run, wait for debugger to be hit
when you start meteor in your meteor app folder, you'll see that "debugger listening on port 5858" in console.
On Meteor 1.0.3.1 (update to Sergey.Simonchik answer)
Start your server with meteor run --debug-port=<port-number>
Point browser to http://localhost:6222/debug?port=<port-number>
Where <port-number> is a port you specify.
In your code add a debugger; where you want to set your break point.
Depending on where debugger; is invoked, it will either break on your client or server browser window with inspector opened.
I like to set breakpoints via a GUI. This way I don't have to remember to remove any debugging code from my app.
This is how I managed to do it server side for my local meteor app:
meteor debug
start your app this way.
Open Chrome to the address it gives you. You MAY need to install https://github.com/node-inspector/node-inspector (it might come bundled with Meteor now? not sure)
You'll see some weird internal meteor code (not the app code you wrote). Press play to run the code. This code simply starts up your server to listen for connections.
Only after you press play you'll see a new directory in your debugger folder structure called "app". In there are your meteor project files. Set a breakpoint in there one the line you want.
Open the local address of your app. This will run your server side code and you you should be able to hit your breakpoint!
Note: you have to reopen the inspector and go through this process again each time your app restarts!
As of Meteor 1.0.2 probably the best way for server-side debugging is directly via the new built-in shell: with running server run meteor shell. More info here: https://www.meteor.com/blog/2014/12/19/meteor-102-meteor-shell
I am not sure why it was not working for you.
I am able to use it by following steps on console (Mac).
$ ps
$ kill -s USR1 *meteor_node_process_id*
$ node-inspector &
Above steps are mentioned on https://github.com/dannycoates/node-inspector. It is for attaching node-inspector to running node process.
I wrote a small meteor package called meteor-inspector which simplifies the use of node-inspector to debug meteor apps. It internally manages the lifecycle of node-inspector and hence, the user does not need to restart the debugger manually after some files have changed.
For more details and concrete usage instructions take a look at https://github.com/broth-eu/meteor-inspector.
for meteor 1.3.5.2, run
meteor debug --debug-port 5858+n
n is a non-zero number, this will cause node-inspector use 8080+n as web port.
WebStorm, the powerful IDE free for open source developers, makes it much easier to debug server-side.
I've tested it on Windows, and the configuration was painless - see my answer.
A inspector that solve my issues is meteor server console. Here is the process I followed to install it:
In your project folder, add the smart package server-eval:
mrt add server-eval
For Meteor 1.0:
meteor add gandev:server-eval
Restart meteor.
Download crx Chrome extension file from here.
Open extensions page in Chrome and drag crx file to extensions page.
Restart Chrome.
Check the web inspector out to eval server side code:
In comparison with node-inspector, I have a clearer output.
If you prefer to use nodeJS' official debugger you can call NODE_OPTIONS='--debug' meteor and then (on a different shell) node debug localhost:5858.