add devcontainer support

.devcontainer/.gdbinit

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+# gdbpg.py contains scripts to nicely print the postgres datastructures
+# while in a gdb session. Since the vscode debugger is based on gdb this
+# actually also works when debugging with vscode. Providing nice tools
+# to understand the internal datastructures we are working with.
+source /root/gdbpg.py
+
+# when debugging postgres it is convenient to _always_ have a breakpoint
+# trigger when an error is logged. Because .gdbinit is sourced before gdb
+# is fully attached and has the sources loaded. To make sure the breakpoint
+# is added when the library is loaded we temporary set the breakpoint pending
+# to on. After we have added out breakpoint we revert back to the default
+# configuration for breakpoint pending.
+# The breakpoint is hard to read, but at entry of the function we don't have
+# the level loaded in elevel. Instead we hardcode the location where the
+# level of the current error is stored. Also gdb doesn't understand the
+# ERROR symbol so we hardcode this to the value of ERROR. It is very unlikely
+# this value will ever change in postgres, but if it does we might need to
+# find a way to conditionally load the correct breakpoint.
+set breakpoint pending on
+break elog.c:errfinish if errordata[errordata_stack_depth].elevel == 21
+set breakpoint pending auto
+
+echo \n
+echo ----------------------------------------------------------------------------------\n
+echo when attaching to a postgres backend a breakpoint will be set on elog.c:errfinish \n
+echo it will only break on errors being raised in postgres \n
+echo \n
+echo to disable this breakpoint from vscode run `-exec disable 1` in the debug console \n
+echo this assumes it's the first breakpoint loaded as it is loaded from .gdbinit \n
+echo this can be verified with `-exec info break`, enabling can be done with \n
+echo `-exec enable 1` \n
+echo ----------------------------------------------------------------------------------\n
+echo \n

.devcontainer/.gitignore

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+postgresql-*.tar.bz2

.devcontainer/.psqlrc

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+\timing on
+\pset linestyle unicode
+\pset border 2
+\setenv PAGER 'pspg --no-mouse -bX --no-commandbar --no-topbar'
+\set HISTSIZE 100000
+\set PROMPT1 '\n%[%033[1m%]%M %n@%/:%> (PID: %p)%R%[%033[0m%]%# '
+\set PROMPT2 '  '

.devcontainer/.vscode/Pipfile

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+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+docopt = "*"
+
+[dev-packages]
+
+[requires]
+python_version = "3.9"

.devcontainer/.vscode/generate_c_cpp_properties-json.py

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+#! /usr/bin/env pipenv-shebang
+"""Generate C/C++ properties file for VSCode.
+
+Uses pgenv to iterate postgres versions and generate
+a C/C++ properties file for VSCode containing the
+include paths for the postgres headers.
+
+Usage:
+  generate_c_cpp_properties-json.py <target_path>
+  generate_c_cpp_properties-json.py (-h | --help)
+  generate_c_cpp_properties-json.py --version
+
+Options:
+  -h --help     Show this screen.
+  --version     Show version.
+
+"""
+import json
+import subprocess
+
+from docopt import docopt
+
+
+def main(args):
+    target_path = args['<target_path>']
+
+    output = subprocess.check_output(['pgenv', 'versions'])
+    # typical output is:
+    #      14.8      pgsql-14.8
+    #  *   15.3      pgsql-15.3
+    #      16beta2    pgsql-16beta2
+    # where the line marked with a * is the currently active version
+    #
+    # we are only interested in the first word of each line, which is the version number
+    # thus we strip the whitespace and the * from the line and split it into words
+    # and take the first word
+    versions = [line.strip('* ').split()[0] for line in output.decode('utf-8').splitlines()]
+
+    # create the list of configurations per version
+    configurations = []
+    for version in versions:
+        configurations.append(generate_configuration(version))
+
+    # create the json file
+    c_cpp_properties = {
+        "configurations": configurations,
+        "version": 4
+    }
+
+    # write the c_cpp_properties.json file
+    with open(target_path, 'w') as f:
+        json.dump(c_cpp_properties, f, indent=4)
+
+
+def generate_configuration(version):
+    """Returns a configuration for the given postgres version.
+
+    >>> generate_configuration('14.8')
+    {
+        "name": "Citus Development Configuration - Postgres 14.8",
+        "includePath": [
+            "/usr/local/include",
+            "/home/citus/.pgenv/src/postgresql-14.8/src/**",
+            "${workspaceFolder}/**",
+            "${workspaceFolder}/src/include/",
+        ],
+        "configurationProvider": "ms-vscode.makefile-tools"
+    }
+    """
+    return {
+        "name": f"Citus Development Configuration - Postgres {version}",
+        "includePath": [
+            "/usr/local/include",
+            f"/home/citus/.pgenv/src/postgresql-{version}/src/**",
+            "${workspaceFolder}/**",
+            "${workspaceFolder}/src/include/",
+        ],
+        "configurationProvider": "ms-vscode.makefile-tools"
+    }
+
+
+if __name__ == '__main__':
+    arguments = docopt(__doc__, version='0.1.0')
+    main(arguments)

.devcontainer/.vscode/launch.json

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+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Attach Citus (devcontainer)",
+            "type": "cppdbg",
+            "request": "attach",
+            "processId": "${command:pickProcess}",
+            "program": "/home/citus/.pgenv/pgsql/bin/postgres",
+            "additionalSOLibSearchPath": "/home/citus/.pgenv/pgsql/lib",
+            "setupCommands": [
+                {
+                    "text": "handle SIGUSR1 noprint nostop pass",
+                    "description": "let gdb not stop when SIGUSR1 is sent to process",
+                    "ignoreFailures": true
+                }
+            ],
+        },
+        {
+            "name": "Open core file",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "/home/citus/.pgenv/pgsql/bin/postgres",
+            "coreDumpPath": "${input:corefile}",
+            "cwd": "${workspaceFolder}",
+            "MIMode": "gdb",
+        }
+    ],
+    "inputs": [
+        {
+            "id": "corefile",
+            "type": "command",
+            "command": "extension.commandvariable.file.pickFile",
+            "args": {
+                "dialogTitle": "Select core file",
+                "include": "**/core*",
+            },
+        },
+    ],
+}