Each poll of a host's overview graph held a worker for one second between
two CPU samples. The answer now carries its sample, signed with the time
and the compute; the next poll sends it back and the usage is taken since
then, so a point is the average since the previous one (normally 5 s, at
most 15 s). Without a sample, or with one that is altered, older or from
another host, or when the host restarted, it is measured over one second
as before.
A sample is one reading; the busy share was mixed from separate readings,
counted guest time twice (it is part of user) and added half a percent.
A host that cannot be read leaves a gap in both graphs instead of a zero
CPU point and a broken memory axis.
The instance lists, the VM page header and the power tab knew three
libvirt states: running, paused and shut off. A VM that was blocked,
shutting down, crashed, suspended by its guest or without a state got
an empty status cell and no actions, so a crashed VM could not even be
forced off from the list. The lists also offered actions users could
not use: Suspend and Resume (views for superusers) to everyone, and
power actions to users who see every VM through the read-only
view_instances permission.
instances/states.py holds the rules in one place: the label and color
of each state, the actions each state allows, and which of them a user
may use (superusers all; a VM's owners all but suspend and resume, and
nothing on a VM an administrator suspended, as the VM page already
showed; nobody else any). Blocked is a running VM; shutting down,
crashed and suspended by the guest get Force Off, after which the VM
can be started. A shut-off template offers Clone to whoever has the
clone permission, as the clone view allows.
The templates read them through two tags (vm_states): the lists and the
VM page header show the state, instance_actions.html has one slot per
button, each enabled or disabled from the allowed actions. The power
tab offers Force Off in the states that need it.
The new tests check the rules directly and render every state in the
lists and on the VM page for a superuser, an owner and a
view_instances user; they fail on the previous code.
The VM page polls the VM state every 5 s and, while its Stats tab is
open, the statistics every 10 s; the compute overview polls the host
graph every 5 s. All used setInterval:
- A new request went out on schedule while the previous one was still
open. When a host goes silent, a stats request waits up to 30-45 s,
so each open page held several sync workers at once.
- Each time the Stats tab was shown, the page made new charts and a
new interval without stopping the old ones, and polling went on on
the other tabs of the page.
- Hidden pages kept polling at full rate.
Measured in a browser against a test server (old code / new): Stats tab
shown 4 times, 31 s on it: 12 / 2 requests; 31 s on another tab of the
page: 12 / 0; page hidden for 31 s: 15 / 0, and the new code asks once
right after the page is shown again; with 25 s answers, at most 15 / 1
requests open at once.
static/js/poll.js repeats a request while the page is visible: the
next one 5 or 10 s after the previous answer, none while hidden, one at
once when shown again. The Stats tab makes its charts once and polls
only while shown. The answer handler runs after the poller's own
bookkeeping, so an error in it (a chart for a disk added meanwhile)
does not stop the polling. A Node test of poll.js runs with the test
suite when node is installed.
The overview page decided whether the host is up with a TCP probe of
the compute's hostname. For an ssh compute named by an ssh_config alias
or reached through ProxyJump, that name and port cannot be reached from
WebVirtCloud directly, so the probe failed while the connection worked:
the page showed the host details and never started the CPU and memory
graphs. The overview now uses Compute.status, the connection
WebVirtCloud uses for everything else.
The compute list shows why a host is not connected (Compute.connection_error)
under "Not Connected", for example a host key verification failure.
Checked against the ssh compute of the test setup through an
ssh_config alias: the previous code renders the overview with the
graphs off, the new one with them on. Both new tests fail on the
previous code.
The instance lists read each VM from libvirt while rendering. When that
failed, the libvirt error replaced the whole page with the error page:
one VM removed out of band, or a host that is down, took the index or
a compute's instances page with it. To avoid that, both index views
left out every VM of a host that was not connected, so users saw their
VMs disappear.
- Instance.info is None when the VM cannot be read. The row then shows
the name and owners from the database, the state "Unknown", and no
title, vCPU, memory or actions.
- Both index views list the VMs of a host that is down. The grouped
view marks the host "Not Connected" and leaves out its CPU and memory.
- A compute's instances page shows the connection error, and no longer
says the hypervisor has no instances when it cannot be reached.
Checked against the test hosts with an unreachable compute added: both
index views list its VM as unknown next to the real VMs. The first
load takes 5.5 s (one bounded connection attempt), the next ones
0.1 s. The new tests fail on the previous code (VMs left out, error
pages).
The VM rows of the instance lists used instance.proxy.instance.info in
every state check, the vCPU column and the action buttons. A template
calls the method on each lookup, so every row made 7 virDomainGetInfo
RPCs (8 on a compute's instances page), and the memory column read the
domain XML once more.
- Instance.info reads virDomainGetInfo once per request; the lists and
instance_actions.html use it.
- The memory column of both index views comes from the same info
(current memory) instead of the domain XML. The value is the same:
checked against currentMemory for every running and shut-off VM of
the test hosts.
A row now makes one info call and one XML read (the title). The new
test counts the calls in the grouped and non-grouped index and on the
compute instances page; it fails on the previous code with 7 and 8
calls.
When a compute can not be connected (for whatever reason) mark it as
not connected in the template.
The generic check
if compute.status
is not enough because the status variable can contain a string with a
connection error.
When a compute can not be connected (for whatever reason) mark it as
not connected in the template.
The generic check
if compute.status
is not enough because the status variable can contain a string with a
connection error.
