Best way to update PHP version on bedrock wordpress site - php

Question

I updated the language of my question, because the original question seemed to be worded in a confusing way (evident from downvotes and unhelpful comments). Hope this makes more sense.
Hi, I'm trying to upgrade the PHP version on a site, I followed this thread and it worked nicely on my development site - I basically changed all instance of PHP "7.1" in the trellis directory to "7.4", and required a PHP version of at least 7.4 in composer and ran composer update.
I happily pushed the update to the staging site, but when I attempted to provision the server with ansible-playbook server.yml -e env=staging, I received the following error:
TASK [Install Python 2.x] ************************************************************************************* ***********************************
System info:
Ansible 2.3.0.0; Linux
Trellis at "Update PHP from 7.1 to 7.4"
---------------------------------------------------
Shared connection to 107.170.41.149 closed.
fatal: [107.170.41.149]: FAILED! => {"changed": false, "failed": true, "rc": 100, "stderr": "Shared connection to 107.170.41.149 closed.\r\n", "stdout": "/usr/bin/python\r\nE: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).\r\n", "stdout_lines": ["/usr/bin/python", "E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution)."]}
Ansible seems to be getting stuck on the "Install Python 2." task. The staging server cannot be provisioned, and when I run php -v on the server it says it's running PHP 7.2.
How do I update PHP? I am avoiding doing it manually, because my gut's telling me there's a special roots way.
The server in question is Ubuntu 16.04 running PHP 7.2 (as mentioned above).
Below is the verbose output of the error from provisioning the staging server:
System info:
Ansible 2.3.0.0; Linux
Trellis at "Update PHP from 7.1 to 7.4"
---------------------------------------------------
OpenSSH_7.6p1 Ubuntu-4, OpenSSL 1.0.2n 7 Dec 2017
debug1: Reading configuration data /home/jill/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: auto-mux: Trying existing master
debug2: fd 3 setting O_NONBLOCK
debug2: mux_client_hello_exchange: master version 4
debug3: mux_client_forwards: request forwardings: 0 local, 0 remote
debug3: mux_client_request_session: entering
debug3: mux_client_request_alive: entering
debug3: mux_client_request_alive: done pid = 16490
debug3: mux_client_request_session: session request sent
debug1: mux_client_request_session: master session id: 2
debug3: mux_client_read_packet: read header failed: Broken pipe
debug2: Received exit status from master 100
Shared connection to 107.170.41.149 closed.
fatal: [107.170.41.149]: FAILED! => {
"changed": false,
"failed": true,
"rc": 100,
"stderr": "OpenSSH_7.6p1 Ubuntu-4, OpenSSL 1.0.2n 7 Dec 2017\r\ndebug1: Reading configuration data /home/jill/.ssh/config\r\ndebug1: Reading configuration data /etc/ssh/ssh_config\r\ndebug1: /etc/ssh/ssh_config line 19: Applying options for *\r\ndebug1: auto-mux: Trying existing master\r\ndebug2: fd 3 setting O_NONBLOCK\r\ndebug2: mux_client_hello_exchange: master version 4\r\ndebug3: mux_client_forwards: request forwardings: 0 local, 0 remote\r\ndebug3: mux_client_request_session: entering\r\ndebug3: mux_client_request_alive: entering\r\ndebug3: mux_client_request_alive: done pid = 16490\r\ndebug3: mux_client_request_session: session request sent\r\ndebug1: mux_client_request_session: master session id: 2\r\ndebug3: mux_client_read_packet: read header failed: Broken pipe\r\ndebug2: Received exit status from master 100\r\nShared connection to 107.170.41.149 closed.\r\n",
"stdout": "/usr/bin/python\r\nE: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).\r\n",
"stdout_lines": [
"/usr/bin/python",
"E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution)."
]
}

Answer 1

This is neither a PHP composer nor a Python problem nor an Ansible problem. The underlying operating system (Ubuntu) has a problem with its apt libraries. The error comes from APT. Sadly you didn't tell us, what ansible module you use in the task named "Install Python 2.x".
Try 'apt-get -f install' with no packages
I think, some package installations hang on the system and need to be installed or configured. This may not have anything to do with your current job of upgrading PHP. Something went wrong in the past. APT will continue to stop operating til this issue is solved. Normally you would do it manually and have a look at the output of apt-get -f install to get an advice of what is the problem with that system. I think it will try to fix the issue automatically or throw an error what is the real issue (for example with two packages that cannot be installed at the same time or a file or directory that is missing or contains wrong values).
This is nothing "normal" which should happen all the time, when you update 100 hosts. This is very specific and part of the so called "configuration gap". Of course -if you dont want to login manually- you can ignore that error in your playbook task, but register the result, if the task failes, check, if the error messages in the registered var contains the above message in stderr and call a command module in your playbook. This would be a little bit of "self-healing".
Something like this
- package:
name: "..."
ignore_errors: true
register: installation
- shell: "apt -f install"
register: self_healing
when:
- "installation is failed"
- "'apt -f install' in installation.stderr"
- debug:
var: self_healing
when: "self_healing is defined"