When you want to watch communication between RHSM clients (subscription-manager, rhsm.service, virt-who, etc.) and Candlepin server, then you can use several complicated solutions (Wireshark, parsing logs of Candlepin server) and one simple solution that is introduced in this document.
Every RHSM application using rhsm Python package can set following environment variables:
SUBMAN_DEBUG_PRINT_REQUESTSUBMAN_DEBUG_PRINT_REQUEST_HEADERSUBMAN_DEBUG_PRINT_REQUEST_BODYSUBMAN_DEBUG_PRINT_RESPONSEWhen you set these environment to any value (it can be 1 or true or anything else), then client application using rhsm module will start to print informations to standard output about HTTP requests.
NOTE: this functionality was introduced in RHEL8.3 in subscription-manager-1.27.11-1
When you set this environment variable: export SUBMAN_DEBUG_PRINT_REQUEST=1, then you can get following output subscription-manager:
[root@localhost ~]# subscription-manager version
Making request: GET /candlepin/
Making request: GET /candlepin/status
server type: Red Hat Subscription Management
subscription management server: 3.1.21-1
subscription management rules: 5.41
subscription-manager: 1.28.3-1.git.1.21e89c8.fc32
As you can see subscription-manager prints not only usual output, but there are all HTTP requests.
When this environment is set using: export SUBMAN_DEBUG_PRINT_REQUEST_HEADER=1, then HTTP headers are also printed to standard output. Example:
[root@localhost ~]# subscription-manager version
Making request: GET /candlepin/ {'Content-type': 'application/json', 'Accept': 'application/json', 'x-subscription-manager-version': '1.28.3-1.git.1.21e89c8.fc32', 'Accept-Language': 'cs-cz', 'X-Correlation-ID': '09214a14cb7147d2a3597ae2f04097b3', 'User-Agent': 'RHSM/1.0 (cmd=subscription-manager) subscription-manager/1.28.3-1.git.1.21e89c8.fc32', 'Content-Length': '0'}
Making request: GET /candlepin/status {'Content-type': 'application/json', 'Accept': 'application/json', 'x-subscription-manager-version': '1.28.3-1.git.1.21e89c8.fc32', 'Accept-Language': 'cs-cz', 'X-Correlation-ID': '09214a14cb7147d2a3597ae2f04097b3', 'User-Agent': 'RHSM/1.0 (cmd=subscription-manager) subscription-manager/1.28.3-1.git.1.21e89c8.fc32', 'Content-Length': '0'}
server type: Red Hat Subscription Management
subscription management server: 3.1.21-1
subscription management rules: 5.41
subscription-manager: 1.28.3-1.git.1.21e89c8.fc32
When this environment variable is set, then body of HTTP request is printed.
[root@localhost ~]# subscription-manager register --username admin --password admin --org admin
...
Making request: POST /candlepin/consumers?owner=admin {'Content-type': 'application/json', 'Accept': 'application/json', 'x-subscription-manager-version': '1.28.3-1.git.1.21e89c8.fc32', 'Accept-Language': 'cs-cz', 'X-Correlation-ID': '8ccc84b060a14fca9ebbc3deb2c2d058', 'Authorization': 'Basic YWRtaW46YWRtaW4=', 'User-Agent': 'RHSM/1.0 (cmd=subscription-manager) subscription-manager/1.28.3-1.git.1.21e89c8.fc32'} {"type": "system", "name": "localhost", ... }
When this environment variable is set, then response from Candlepin server is printed
[root@localhost ~]# subscription-manager version
Making request: GET /candlepin/ {'Content-type': 'application/json', 'Accept': 'application/json', 'x-subscription-manager-version': '1.28.3-1.git.1.21e89c8.fc32', 'Accept-Language': 'cs-cz', 'X-Correlation-ID': 'a90da8ffd1304846973da3e51c0bafc7', 'User-Agent': 'RHSM/1.0 (cmd=subscription-manager) subscription-manager/1.28.3-1.git.1.21e89c8.fc32', 'Content-Length': '0'}
200 {'Server': 'Apache-Coyote/1.1', 'x-candlepin-request-uuid': '8d4583a9-2557-49db-84d3-03c652757654', 'X-Version': '3.1.21-1', 'Content-Type': 'application/json', 'Transfer-Encoding': 'chunked', 'Date': 'Thu, 24 Sep 2020 09:18:22 GMT'}
[ {
"rel" : "activation_keys",
"href" : "/activation_keys"
}]
Making request: GET /candlepin/status {'Content-type': 'application/json', 'Accept': 'application/json', 'x-subscription-manager-version': '1.28.3-1.git.1.21e89c8.fc32', 'Accept-Language': 'cs-cz', 'X-Correlation-ID': 'a90da8ffd1304846973da3e51c0bafc7', 'User-Agent': 'RHSM/1.0 (cmd=subscription-manager) subscription-manager/1.28.3-1.git.1.21e89c8.fc32', 'Content-Length': '0'}
200 {'Server': 'Apache-Coyote/1.1', 'x-candlepin-request-uuid': 'f10df173-9a70-4bf5-b803-ba2b5b8e0180', 'X-Version': '3.1.21-1', 'Content-Type': 'application/json', 'Transfer-Encoding': 'chunked', 'Date': 'Thu, 24 Sep 2020 09:18:22 GMT'}
{
"mode" : "NORMAL",
"modeReason" : null,
"modeChangeTime" : null,
"result" : true,
"version" : "3.1.21",
"rulesVersion" : "5.41",
"release" : "1",
"standalone" : true,
"timeUTC" : "2020-09-24T09:18:22+0000",
"rulesSource" : "default",
"managerCapabilities" : [ "instance_multiplier", "derived_product", "vcpu", "cert_v3", "hypervisors_heartbeat", "remove_by_pool_id", "syspurpose", "insights_auto_register", "storage_band", "cores", "hypervisors_async", "org_level_content_access", "guest_limit", "ram", "batch_bind" ]
}
It is good to create two scripts for switching debug prints on and off.
The script could look like this and can be saved in e.g. ~/bin/debug_subman_set.sh
#!/bin/bash
export SUBMAN_DEBUG_PRINT_REQUEST=1
export SUBMAN_DEBUG_PRINT_REQUEST_HEADER=1
export SUBMAN_DEBUG_PRINT_REQUEST_BODY=1
export SUBMAN_DEBUG_PRINT_RESPONSE=1
It is worth to mention that you have to execute this script using source command:
source ~/bin/debug_subman_set.sh
You have to use source, because you want to set environment variables in current shell.
Script for switching off could look like this:
#!/bin/bash
unset SUBMAN_DEBUG_PRINT_REQUEST
unset SUBMAN_DEBUG_PRINT_REQUEST_HEADER
unset SUBMAN_DEBUG_PRINT_REQUEST_BODY
unset SUBMAN_DEBUG_PRINT_RESPONSE