Unable to access github API getting bad credentials error

Question

I am trying to add a custom code check for a PR. After doing some research I found out that it can be done using the API mentioned below.

POST /repos/{owner}/{repo}/check-runs

Initially, it was giving me this error:

{
    "message": "You must authenticate via a GitHub App.",
    "documentation_url": "https://docs.github.com/rest/reference/checks#create-a-check-run"
}

I followed the guideline provided in this link.

I created a GitHub app.
Gave it required permission.
Generated a private key.
Generated a JWT token using the private key.
Installed the Github app in the repo too

I created a curl request:

curl --location --request POST 'https://api.github.com/repos/X/X-app/check-runs' \
--header 'Accept: application/vnd.github.v3+json' \
--header 'Authorization: Bearer eyJhbGciOiJSUzI1NiJ9.X.X-X-SAFvDnSkaJDjMI2T_BAC2iLlRZ7uNyFSe-X-UgFBFjoFrwsbcYFKfDM8f3FNPYpA6afhr18DLZ6rzu35klA' \
--header 'Content-Type: application/json' \
--data-raw '{
    "name": "loremipsum"
}'

But, now I am getting this error

{
    "message": "Bad credentials",
    "documentation_url": "https://docs.github.com/rest"
}

I am not sure what I am missing here.

ruakh · Accepted Answer · 2025-03-17 02:59:05Z

26

I figured this out. The GitHub documentation is a bit unclear/misleading.

You don't pass the app's JWT bearer token directly to the "Create a check run" API; instead, you use that bearer token to get an access token for a specific installation, and then you pass that token to the "Create a check run" API.

To get that access token, you need the installation-ID; if you don't already have it, you can use the app's JWT bearer token to list your installations:

curl -i \
  -H "Authorization: Bearer YOUR_JWT" \
  -H "Accept: application/vnd.github.v3+json" \
  https://api.github.com/app/installations

Once you know the installation-ID, you can use the app's JWT bearer token to get an access token for the installation:

curl -i -X POST \
  -H "Authorization: Bearer YOUR_JWT" \
  -H "Accept: application/vnd.github.v3+json" \
  https://api.github.com/app/installations/THE_INSTALLATION_ID/access_tokens

You can then use that access token to call GitHub APIs on that repo:

curl -i \
  -H "Authorization: token YOUR_INSTALLATION_ACCESS_TOKEN" \
  ...

(Note that for this one you write token instead of Bearer.)

edited Mar 17 at 2:59

ruakh

185k29 gold badges292 silver badges324 bronze badges

answered Aug 2, 2021 at 19:59

KKS

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5 Comments

Bean Taxi Over a year ago

I believe the /app/installations call needs to be a GET, not a POST. I get a 404 on POST but GET works fine.

KKS Over a year ago

you're right, the first one is a GET. Thanks!

Bean Taxi Over a year ago

Np! Great answer btw; just upvoted

Charles Morin Over a year ago

Worked for me. Been struggling for a while to get an access token for testing behavior of a GitHub App. GitHub's documentation is indeed missing this crucial part.

digitalsy Over a year ago

omg thank you for this! Github's documentation seems great at first but clearly doesn't outline everything you need to do to auth properly. This post was VERY helpful. Thank you!

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