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Curl and OAuth

Sometimes when working on APIs you need (or want) to use curl. Here's how to do that with the IT Lab OAuth 2.0 Authorization Server (AS):

% CREDS=$(jq -r '.client_id + ":" + .client_secret' creds.json)
% SCOPES=scope1+scope2
% curl -o token.json -s -u "${CREDS}" -d scope="${SCOPES}" \
> -d grant_type=client_credentials ${AUTHZ_URL}/token
% TOKEN=$(jq -r .access_token token.json)

This assumes that you have a file called creds.json that contains your OAuth 2.0 client_id and client_secret:

  "client_id": "my-client",
  "client_secret": "superSecr3t"

Once TOKEN is set, you can use curl to make API calls:

% AUTHZ="Authorization: Bearer ${TOKEN}"
% API=
% curl -H "${AUTHZ}" -s ${API}/check | jq .
  "user": {
    "username": "my-client"
  "authInfo": {
    "active": true,
    "scope": "someapi:read someapi:write",
    "expires_at": "2017-12-19T17:00:26-0800",
    "exp": 1513731626,
    "sub": "my-client",
    "client_id": "my-client",
    "token_type": "Bearer",
    "scopes": [

jq is a very useful JSON parser, filter, and formatter. If you're on a Mac with Homebrew, installing jq is as simple as

% brew install jq

API Scopes

Different APIs use different scopes:

CertCache API

  • certcache:read - Read only access
  • certcache:write - Write access