Back to basics: Using curl in the SAP enterprise landscape

There are many HTTP clients to use when exploring and consuming resources in the SAP enterprise landscape. Learn what you need to know about the powerful command-line HTTP client curl in this episode. Everyone welcome, especially beginners!

Discussion:

Topics:
HTTP, curl, command line, SAP Service Manager, SAP Business Technology Platform, OAuth 2.0, btp CLI, pass, jq, ijq

Links:

Chapters:
00:00 Welcome and introduction
07:00 Off to the SAP Business API Hub to look at the task in hand
08:30 Examining the Service Manager API
10:22 Looking at the SAP Help Portal docu on how to get an access token and authenticate the calls
10:40 Considering the two OAuth 2.0 flows in use
11:15 Realising I'm an idiot and had completely missed the content-type header in my quiz question
13:36 Examining the docu's curl sample to retrieve a token
16:02 Exploring curl's help features
18:10 Considering HTTP POST and curl's many facilities for that
19:00 A short digression into getting curl to follow redirects with --location, and an examination of --verbose output
26:20 Looking at a more comfortable way to express x-www-form-urlencoded name/value pairs with multiple --data parameters
30:15 Digging into why the authenticated request for an access token failed: lack of URL encoding of the values
32:30 Examining the --data-urlencode parameter option, as opposed to --data
35:17 Comparing --include (show the response headers) with --verbose
36:19 Celebrating the receipt of an access token
38:40 Trying out a deliberately over-simplified curl request (without authentication)
41:10 Adding, with the --header parameter, a specific Authorization header
41:33 Comparing that with the use of --user which generates an Authorization header with some Base64 encoded string for a Basic authentication header automatically
44:15 A successfully authenticated call to the /v1/service_offerings endpoint
45:28 Avoiding curl's progress indicators with --silent
46:55 Getting ready to create a service instance with a POST request and a file-based payload with the @ mechanism of curl's --data parameter
50:22 'Useless use of cat' award from shellcheck, hurray!
52:00 Examining why we received an error "unsupported media type"
52:48 An unexpected but always welcome WhatsApp call from my son Joseph
53:40 Fixing the call with another --header parameter to specify that the Content-Type is of the payload I'm sending is application/json (curl sends application/x-www-form-urlencoded by default)
54:02 Getting a lovely HTTP 201 CREATED response (altho the Location header is missing) and checking the result with ijq and also the btp CLI
57:00 Finally, using curl to delete the instance (with the --request DELETE parameter)