path: root/yarns.webapp/900-implementations.yarn

Implementations
===============

This chapter includes IMPLEMENTS sections for the various steps used
in scenarios.

Managing a WEBAPP instance
--------------------------

We're testing a web application (convenivently named WEBAPP, though
the executable is `lorry-controller-webapp`), so we need to be able to
start it and stop it in scenarios. We start it as a background
process, and keep its PID in `$DATADIR/webapp.pid`. When it's time to
kill it, we kill the process with the PID in that file. This is not
perfect, though it's good enough for our purposes. It doesn't handle
running multiple instances at the same time, which we don't need, and
doens't handle the case of the process dying and the kernel re-using
the PID for something else, which is quite unlikely.

Start an instance of the WEBAPP, using a random port. Record the PID
and the port. Listen only on localhost. We use `start-stop-daemon` to
start the process, so that it can keep running in the background,
but the shell doesn't wait for it to terminate. This way, WEBAPP will
be running until it crashes or is explicitly killed.

    IMPLEMENTS GIVEN a running WEBAPP
    start_webapp

    IMPLEMENTS WHEN WEBAPP is started
    start_webapp

Kill the running WEBAPP, using the recorded PID. We need to do this
both as a WHEN and a FINALLY step.

    IMPLEMENTS WHEN WEBAPP is terminated
    kill_daemon_using_pid_file "$DATADIR/webapp.pid"

    IMPLEMENTS FINALLY WEBAPP terminates
    kill_daemon_using_pid_file "$DATADIR/webapp.pid"

Also test that WEBAPP isn't running.

    IMPLEMENTS THEN WEBAPP isn't running
    pid=$(head -n1 "$DATADIR/webapp.pid")
    if kill -0 "$pid"
    then
        echo "process $pid is still running, but shouldn't be" 1>&2
        exit 1
    fi

Managing Lorry Controller configuration
---------------------------------------

We need to be able to create, and change, the `lorry-controller.conf`
file, and other files, in CONFGIT. First of all, we need to create
CONFGIT.

    IMPLEMENTS GIVEN a new git repository in (\S+)
    git init "$DATADIR/$MATCH_1"

Then we need to create an empty `lorry-controller.conf` file there.
This is not just an empty file, it must be a JSON file that contains
an empty list object.

    IMPLEMENTS GIVEN an empty lorry-controller.conf in (\S+)
    printf '[]\n' > "$DATADIR/$MATCH_1/lorry-controller.conf"

Set the contents of `lorry-controller.conf` from a textual form.

    IMPLEMENTS GIVEN a lorry-controller.conf in (\S+) containing "(.*)"$
    printf '%s\n' "$MATCH_2" > "$DATADIR/$MATCH_1/lorry-controller.conf"

Add a `.lorry` file to be used by a `lorry-controller.conf`.

    IMPLEMENTS GIVEN Lorry file (\S+) with (.*)
    printf '%s\n' "$MATCH_2" > "$DATADIR/$MATCH_1"

Remove a file. This is actually quite generic, but it's relevant to us
for `.lorry` files only (when this is being written).

    IMPLEMENTS GIVEN file (\S+) is removed
    rm "$DATADIR/$MATCH_1"

Add a `lorries` section to a `lorry-controller.conf`. This hardcodes
most of the configuration.

    IMPLEMENTS GIVEN (\S+) in (\S+) adds lorries (\S+) using prefix (\S+)
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3, MATCH_4 = yarnlib.matches()

    new = {
        "type": "lorries",
        "interval": "0s",
        "prefix": MATCH_4,
        "globs": [
            MATCH_3,
        ],
    }

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)
    obj = yarnlib.load_json_from_file(filename)
    obj.append(new)
    yarnlib.dump_json_to_file(obj, filename)
    '

Add a `troves` section to `lorry-controller.conf`. Again, we hardcode
most of the configuration.

    IMPLEMENTS GIVEN (\S+) in (\S+) adds trove (\S+)
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3 = yarnlib.matches()

    new = {
        "type": "troves",
        "trovehost": MATCH_3,
        "protocol": "ssh",
        "interval": "0s",
        "ls-interval": "0s",
        "prefixmap": {},
    }

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)
    obj = yarnlib.load_json_from_file(filename)
    obj.append(new)
    yarnlib.dump_json_to_file(obj, filename)
    '

Set the a specific field for all sections in a `lorry-controller.conf`
file.

    IMPLEMENTS GIVEN (\S+) in (\S+) has (\S+) set to (.+) for everything
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import json
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3, MATCH_4 = yarnlib.matches()

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)

    obj = yarnlib.load_json_from_file(filename)

    for section in obj:
        section[MATCH_3] = json.loads(MATCH_4)

    yarnlib.dump_json_to_file(obj, filename)
    '

Set a specific field for a `troves` section.

    IMPLEMENTS GIVEN (\S+) in (\S+) sets (\S+) to (.+) for trove (\S+)
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import json
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3, MATCH_4, MATCH_5 = yarnlib.matches()

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)

    obj = yarnlib.load_json_from_file(filename)

    for section in obj:
        if section["type"] in ["trove", "troves"]:
            if section["trovehost"] == MATCH_5:
                section[MATCH_3] = json.loads(MATCH_4)

    yarnlib.dump_json_to_file(obj, filename)
    '

Remove a specified field for a `troves` section

    IMPLEMENTS GIVEN (\S+) in (\S+) removes field (\S+) from trove (\S+)
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3, MATCH_4 = yarnlib.matches()

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)
    obj = yarnlib.load_json_from_file(filename)

    for section in obj:
        if section["type"] in ["trove", "troves"]:
            if section["trovehost"] == MATCH_4:
                del section[MATCH_3]

    yarnlib.dump_json_to_file(obj, filename)
    '

Set the prefixmap for a Trove in a Lorry Controller configuration
file. Note that the Trove must already be in the configuration file.

    IMPLEMENTS GIVEN (\S+) in (\S+) has prefixmap (\S+):(\S+) for (\S+)
    cd "$SRCDIR"/yarns.webapp
    python3 -c '
    import os
    import yarnlib

    MATCH_1, MATCH_2, MATCH_3, MATCH_4, MATCH_5 = yarnlib.matches()

    filename = os.path.join(yarnlib.DATADIR, MATCH_2, MATCH_1)
    objs = yarnlib.load_json_from_file(filename)

    for obj in objs:
        if obj["type"] == "troves" and obj["trovehost"] == MATCH_5:
            obj["prefixmap"][MATCH_3] = MATCH_4

    yarnlib.dump_json_to_file(objs, filename)
    '

We need to be able to tell WEBAPP, when it runs, where the
configuration directory is.

    IMPLEMENTS GIVEN WEBAPP uses (\S+) as its configuration directory
    add_to_config_file "$DATADIR/webapp.conf" \
        configuration-directory "$DATADIR/$MATCH_1"

Make WEBAPP fake access to an Upstream Host using a static file.

    IMPLEMENTS GIVEN WEBAPP fakes Upstream Host (\S+)
    add_to_config_file "$DATADIR/webapp.conf" \
        debug-fake-upstream-host "$MATCH_1=$DATADIR/$MATCH_1.trove"

Control the ls listing of an Upstream Host.

    IMPLEMENTS GIVEN Upstream Host (\S+) has repository (\S+)
    filename="$DATADIR/$MATCH_1.trove"
    if [ ! -e "$filename" ]
    then
        echo "{}" > "$filename"
    fi
    cat "$filename"
    python3 -c '
    import json, os, sys
    MATCH_2 = os.environ["MATCH_2"]
    filename = sys.argv[1]
    with open(filename) as f:
        data = json.load(f)
    data["ls-output"] = data.get("ls-output", []) + [MATCH_2]
    with open(filename, "w") as f:
        json.dump(data, f)
    ' "$filename"

Remove a repository from the fake Upstream Host.

    IMPLEMENTS GIVEN Upstream Host (\S+) doesn't have repository (\S+)
    filename="$DATADIR/$MATCH_1.trove"
    if [ ! -e "$filename" ]
    then
        echo "{}" > "$filename"
    fi
    cat "$filename"
    python3 -c '
    import json, os, sys
    MATCH_2 = os.environ["MATCH_2"]
    filename = sys.argv[1]
    with open(filename) as f:
        data = json.load(f)
    paths = data.get("ls-output", [])
    if MATCH_2 in paths:
        paths.remove(MATCH_2)
    data["ls-output"] = paths
    with open(filename, "w") as f:
        json.dump(data, f)
    ' "$filename"

Making and analysing HTTP requests
---------------------------------

Simple HTTP GET and POST requests are simple. We make the request,
sending a body if given, and capture the response: HTTP status code,
response headers, response body.

We make the request using the `curl` command line program, which makes
capturing the response quite convenient.

HTTP requests can be made by various entities. This does not affect
test code, but allows for nicer scenario steps.

We check that the HTTP status indicates success, so that every
scenario doesn't need ot check that separately.

A GET request:

    IMPLEMENTS WHEN admin makes request GET (\S+)
    > "$DATADIR/response.headers"
    > "$DATADIR/response.body"
    port=$(cat "$DATADIR/webapp.port")

    # The timestamp is needed by "THEN static status page got updated"
    touch "$DATADIR/request.timestamp"

    curl \
        -D "$DATADIR/response.headers" \
        -o "$DATADIR/response.body" \
        --silent --show-error \
        "http://127.0.0.1:$port$MATCH_1"
    cat "$DATADIR/response.headers"
    cat "$DATADIR/response.body"
    head -n1 "$DATADIR/response.headers" | grep '^HTTP/1\.[01] 200 '

A POST request always has a body. The body consists of `foo=bar`
pairs, separated by `&` signs.

    IMPLEMENTS WHEN (\S+) makes request POST (\S+) with (.*)
    post_request "$MATCH_2" "$MATCH_3"

Except, sometimes we don't have a useful body to give. So we don't.

    IMPLEMENTS WHEN (\S+) makes request POST (\S+)
    post_request "$MATCH_2" dummy=value

Check the Content-Type of the response has the desired type.

    IMPLEMENTS THEN response is (\S+)
    cat "$DATADIR/response.headers"
    grep -i "^Content-Type: $MATCH_1" "$DATADIR/response.headers"

A JSON response can then be queried further. The JSON is expected to
be a dict, so that values are accessed by name from the dict. The
value is expresssed as a JSON value in the step.

    IMPLEMENTS THEN response has (\S+) set to (.+)
    cat "$DATADIR/response.body"
    python3 -c '
    import json, os, sys
    data = json.load(sys.stdin)
    key = os.environ["MATCH_1"]
    expected = json.loads(os.environ["MATCH_2"])
    value = data[key]
    if value != expected:
        sys.stderr.write(
            "Key {key} has value {value}, but "
            "{expected} was expected".format(
                key=key, value=value, expected=expected))
        sys.exit(1)
    ' < "$DATADIR/response.body"

A JSON response may need to be analysed in more depth. Specifically,
we may need to look at a list of dicts, as below.

    IMPLEMENTS THEN response has (\S+) item (\d+) field (\S+) set to (\S+)
    cat "$DATADIR/response.body"
    python3 -c '
    import json, os, sys
    data = json.load(sys.stdin)
    print("data:", repr(data))
    items = os.environ["MATCH_1"]
    print("items:", repr(items))
    item = int(os.environ["MATCH_2"])
    print("item:", repr(item))
    field = os.environ["MATCH_3"]
    print("field:", repr(field))
    print("match3:", repr(os.environ["MATCH_4"]))
    expected = json.loads(os.environ["MATCH_4"])
    print("expected:", repr(expected))
    print("data[items]:", repr(data[items]))
    print("data[items][item]:", repr(data[items][item]))
    print("data[items][item][field]:", repr(data[items][item][field]))
    value = data[items][item][field]
    if value != expected:
        sys.stderr.write(
            "Item {item} in {items} has field {field} with "
            "value {value}, but {expected} was expected".format (
                item=item, items=items, field=field, value=value,
                expected=expected))
        sys.exit(1)
    ' < "$DATADIR/response.body"

In some cases, such as free disk space, we don't care about the actual
value, but we do care that it is there.

    IMPLEMENTS THEN response has (\S+) set
    cat "$DATADIR/response.body"
    python3 -c '
    import json, os, sys
    data = json.load(sys.stdin)
    key = os.environ["MATCH_1"]
    if key not in data:
        sys.stderr.write(
            "Key {key} is not set, but was expected to be set".format (
                key=key))
        sys.exit(1)
    ' < "$DATADIR/response.body"

Some responses are just plain text, so we match them with a regexp.

    IMPLEMENTS THEN response matches "(.*)"$
    cat "$DATADIR/response.body"
    grep "$MATCH_1" "$DATADIR/response.body"


Running the "remove old jobs" helper program
--------------------------------------------

Lorry Controller comes with a helper program to remove old jobs from
STATEDB. Tests need to be able to run it.

    IMPLEMENTS WHEN admin removes old jobs at (\d+)
    "$SRCDIR/lorry-controller-remove-old-jobs" \
        --log "$DATADIR/remove-old-jobs.log" \
        --webapp-host=127.0.0.1 \
        --webapp-port="$(cat "$DATADIR/webapp.port")" \
        --debug-now="$MATCH_1"

Status web page
---------------

WEBAPP is expected to update a static HTML pages whenever the
`/1.0/status` request is made. We configure WEBAPP to write it to
`$DATADIR/lc-status.html`. We don't test the contents of the page, but
we do test that it gets updated. We test for the updates by comparing
the modification time of the file with the time of the request. We
know the time of the request thanks to the "WHEN admin makes a
request" step updating the modification time of a file for this
purpose.

    IMPLEMENTS THEN static status page got updated
    # test -nt isn't useful: the timestamps might be identical, and
    # that's OK on filesystems that only store full-second timestamps.
    # We generate timestamps in (roughly) ISO 8601 format, with stat,
    # and those can be compared using simple string comparison.

    status=$(stat -c %y "$DATADIR/lc-status.html")
    request=$(stat -c %y "$DATADIR/request.timestamp")
    test "$request" = "$status" || test "$request" '<' "$status"


STATEDB
-------

Check that the STATEDB is empty. This means it should exist, and
should be initialised, but none of the important tables should have
any rows in them.

    IMPLEMENTS THEN STATEDB is empty
    test -s "$DATADIR/webapp.db"
    sqlite3 "$DATADIR/webapp.db" 'SELECT * FROM hosts;' | stdin_is_empty
    sqlite3 "$DATADIR/webapp.db" 'SELECT * FROM lorries;' | stdin_is_empty