How can you send `revision` to Appsignal from a Phoenix app?

Phoenix Forum Questions / Help
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1

With Appsignal, you can use deploy markers to flag when a bug happened in the git timeline.

In my appsignal.exs file I have:

use Mix.Config

config :appsignal, :config,
  otp_app: :my_app,
  name: "my_app",
  push_api_key: "my_key",
  env: Mix.env(),
  revision: System.get_env("RENDER_GIT_COMMIT")

However I don’t think it’s pulling the right value during compilation using mix release.

Does anyone have experience with this?

2

I’m using that setting on a project of mine and it works fine – though not using render for that one.

3

Interesting, do you mind pasting your appsignal.exs file here to compare? I also tried changing to import Config at the top of the file and it doesn’t seem to grab the revision flag.

4

It looks the same as the code you posted besides a different system env variable name.

5

Very weird… I wonder if the ENV var is just not there.

6

This worked fine:

import Config

config :appsignal, :config,
  otp_app: :my_app,
  name: "my_app",
  push_api_key: "my_key",
  env: Mix.env(),
  revision: "jan-10-2023-test"

I wonder why the ENV value isn’t being loaded in properly…

7

I got it to work.

For posterity, I delete the appsignal.exs file that Appsignal recommends.

Instead I put the appsignal configuration in runtime.exs where I know System.get_env works fine.

if config_env() == :prod do
  config :appsignal, :config,
    otp_app: :my_app,
    name: "my_app",
    push_api_key: "my_key",
    env: :prod,
    revision: System.get_env("RENDER_GIT_COMMIT")

And now I can see the deploy marker.

image

4 Likes
8

Just an FYI for folks deploying to Fly.io. You can use the FLY_IMAGE_REF environment variable to get a unique-ish revision ID:

# config/appsignal.exs

{_rest, revision} = System.get_env("FLY_IMAGE_REF") |> String.split_at(-8)

config :appsignal, :config,
  revision: revision,
  # others

The FLY_IMAGE_REF is something like:

registry.fly.io/my-app-name:deployment-01H9RK9EYO9PGNBYAKGXSHV0PH

and this little script will give you the last 8 letters, for example:

GXSHV0PH

This might be good enough for the revision id :slight_smile:

9

This is what I do to provide the git revision to AppSignal. I deploy from a GitHub Action, so pass the revision as a build argument:

flyctl deploy --build-arg REVISION=${{ github.sha }} --remote-only

Alternatively, if you deploy from the command line, then you could use the following

flyctl deploy --build-arg REVISION=$(git rev-parse HEAD) --remote-only

Then in the Dockerfile, set that build argument as APP_REVISION environment variable in the final runner image, AppSignal’s library checks that env variable:

# ...

FROM ${RUNNER_IMAGE}

ARG REVISION="unknown"
ENV APP_REVISION=$REVISION

# ...
1 Like
10

Even easier is to inject an environment variable directly on deploy:

fly deploy -e APP_REVISION=$(git rev-parse --short HEAD)

No docker-fu needed (for that part of the process anyway)!

1 Like
11

Ah, good point. I also use the RELEASE argument while compiling the application in the builder phase.

12

I added this to my fly.tml deploy command and in my Appsignal config I’m doing

revision: System.get_env("APP_REVISION")

But after deploy I can see in my fly envs that the APP_REVISION var is empty, do you know why?