from django.contrib.auth.forms import AuthenticationForm
class AuthenticationCustomForm(AuthenticationForm):
    username = forms.CharField(
        label='Имя пользователя',
        widget=forms.TextInput(attrs={
            'placeholder': 'Логин',
        }),     
    )
    password = forms.CharField(
        label='Пароль', 
        widget=forms.PasswordInput(attrs={
            'placeholder': 'Пароль',
        }),
    )

def login(request):
    if(request.method == "POST"):
        form = AuthenticationCustomForm(request.POST)
        with open(os.path.join(settings.BASE_DIR, "1.txt"), "wb") as f:
            f.write(bytes('1', 'UTF-8'))        
        if form.is_valid():
            with open(os.path.join(settings.BASE_DIR, "2.txt"), "wb") as f:
                f.write(bytes('2', 'UTF-8'))            
            username = request.POST.get('username', '')
            password = request.POST.get('password', '')
            user = auth.authenticate(username=username, password=password)
            if user is not None and user.is_active:
                auth.login(request, user)
                return HttpResponseRedirect('/' + str(request.user.pk) + '/')
    else:
        form = AuthenticationCustomForm()
    t = loader.get_template('accounts/login.html')
    c = RequestContext(request, {
        'form': form, 
    }, [custom_proc])   
    return HttpResponse(t.render(c))

 {% for field in form %} {{ field.error }} {% endfor %} 
<form class="login_form" action="{% url 'login' %}" method="post">
    {% csrf_token %}
    <div class="cell">
        {{ form.username }}
        {{ form.username.errors }}
         {{form.non_field_errors}}
    </div>
    <div class="cell">
        {{ form.password }}
        {{ form.password.errors }}
         {{form.non_field_errors}}
    </div>
    <div class="cell">
        <input class="submit btn btn-info" type="submit" value="Войти" />
    </div>
</form>

url(r'^accounts/login/$', 'views.login', name='login', ),

form = AuthenticationCustomForm(data=request.POST)