Default new apps to tag logs with request_id
#22949
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| with_rails_env "development" do | ||
| app 'development' | ||
| assert_equal [:request_id], Rails.application.config.log_tags |
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Shouldn't this be assert_not_equal?
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In high volume applications it can be very difficult to figure out what is happening in logs because each request is not easily identified. For example 3 requests could look something like this:
```
Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:21 +0000
Rendered welcome/index.html.erb within layouts/application (0.1ms)
Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:22 +0000
Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:23 +0000
Rendered welcome/index.html.erb within layouts/application (0.1ms)
Processing by WelcomeController#index as HTML
Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
Processing by WelcomeController#index as HTML
Rendered welcome/index.html.erb within layouts/application (0.1ms)
Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
Processing by WelcomeController#index as HTML
Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
```
The `:request_id` log tag ensures that each request is tagged with a unique identifier. While they are still interleaved it is possible to figure out which lines belong to which requests. Like:
```
[c6034478-4026-4ded-9e3c-088c76d056f1] Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:21 +0000
[c6034478-4026-4ded-9e3c-088c76d056f1] Rendered welcome/index.html.erb within layouts/application (0.1ms)
[abuqw781-5026-6ded-7e2v-788c7md0L6fQ] Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:22 +0000
[acfab2a7-f1b7-4e15-8bf6-cdaa008d102c] Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:23 +0000
[abuqw781-5026-6ded-7e2v-788c7md0L6fQ] Rendered welcome/index.html.erb within layouts/application (0.1ms)
[c6034478-4026-4ded-9e3c-088c76d056f1] Processing by WelcomeController#index as HTML
[c6034478-4026-4ded-9e3c-088c76d056f1] Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
[abuqw781-5026-6ded-7e2v-788c7md0L6fQ] Processing by WelcomeController#index as HTML
[abuqw781-5026-6ded-7e2v-788c7md0L6fQ] Rendered welcome/index.html.erb within layouts/application (0.1ms)
[abuqw781-5026-6ded-7e2v-788c7md0L6fQ] Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
[acfab2a7-f1b7-4e15-8bf6-cdaa008d102c] Processing by WelcomeController#index as HTML
[acfab2a7-f1b7-4e15-8bf6-cdaa008d102c] Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
```
Now if you have the logs and you find this unique ID you can filter to only look at information from that request. So a filtered log output would be very clear:
```
[c6034478-4026-4ded-9e3c-088c76d056f1] Started GET "/" for 72.48.77.213 at 2016-01-06 20:30:21 +0000
[c6034478-4026-4ded-9e3c-088c76d056f1] Rendered welcome/index.html.erb within layouts/application (0.1ms)
[c6034478-4026-4ded-9e3c-088c76d056f1] Processing by WelcomeController#index as HTML
[c6034478-4026-4ded-9e3c-088c76d056f1] Completed 200 OK in 5ms (Views: 3.8ms | ActiveRecord: 0.0ms)
```
In addition to this benefit the `:request_id` can be set via the `X-Request-ID` header so that the same request could be traced between multiple components. For example a request comes in Nginx (or another load balancer) could assign a request id. As the load balancer processes the request I can log using that id, then when the request is passed on to Rails, the same id is used. That way if a problem is determined to be not caused in Rails it could be traced back to other components with the same ID. You can set a value in nginx for example using something like this:
```
location / {
proxy_pass http://upstream;
proxy_set_header X-Request-Id $pid-$msec-$remote_addr-$request_length;
}
# http://stackoverflow.com/questions/17748735/setting-a-trace-id-in-nginx-load-balancer
```
Heroku sets this header value so problems like timeouts that are logged by like router can be traced back to specific request within the application.
Whether you are using components that are setting request ID or not, all production applications can benefit from the additional debugging information of having a unique identifier for all requests. This change will only affect new applications, anyone can opt out by commenting or removing the line in `config/production.rb`.
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LGTM but since it is changing a default I'll defer to @dhh. |
dhh
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Default new apps to tag logs with `request_id`
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Sounds good to me! Can't imagine not request-id tagging logging in production either. |
|
❤️🚀😄 |
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👍 |
|
😍 |
gbp
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May 23, 2019
- Update comments - Rename serve_static_files to public_file_server.enabled preventing depreciation warnings - Disable mailer caching in Rails 5 - Prevent assets.digest from being set in Rails 5 - Prepend log lines with request ID [1] [1] rails/rails#22949
gbp
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May 28, 2019
- Update comments - Rename serve_static_files to public_file_server.enabled preventing depreciation warnings - Disable mailer caching in Rails 5 - Prevent assets.digest from being set in Rails 5 - Prepend log lines with request ID [1] [1] rails/rails#22949
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In high volume applications it can be very difficult to figure out what is happening in logs because each request is not easily identified. For example 3 requests could look something like this:
The
:request_idlog tag ensures that each request is tagged with a unique identifier. While they are still interleaved it is possible to figure out which lines belong to which requests. Like:Now if you have the logs and you find this unique ID you can filter to only look at information from that request. So a filtered log output would be very clear:
In addition to this benefit the
:request_idcan be set via theX-Request-IDheader so that the same request could be traced between multiple components. For example a request comes in Nginx (or another load balancer) could assign a request id. As the load balancer processes the request I can log using that id, then when the request is passed on to Rails, the same id is used. That way if a problem is determined to be not caused in Rails it could be traced back to other components with the same ID. You can set a value in nginx for example using something like this:Heroku sets this header value so problems like timeouts that are logged by like router can be traced back to specific request within the application.
Whether you are using components that are setting request ID or not, all production applications can benefit from the additional debugging information of having a unique identifier for all requests. This change will only affect new applications, anyone can opt out by commenting or removing the line in
config/production.rb.